/**
  1. Object.is(v1, v2)
    * 判断2个数据是否完全相等
  2. Object.assign(target, source1, source2..)
    * 将源对象的属性复制到目标对象上
  3. 直接操作 __proto__ 属性
    let obj2 = {};
    obj2.__proto__ = obj1;
 */

 console.log(Object.is('123', '123')) //true
 console.log(NaN === NaN) //false NaN跟任何值都不相等
 console.log(Object.is(NaN, NaN)) //true
 console.log(0 == -0) //true
 console.log(0 === -0) //true
 console.log(Object.is(0, -0)) //false

//Object.assign(target, source1, source2..)
const obj1 = {name:'limi',age:31, x:{y: 'z'}}
const obj2 = {}
Object.assign(obj2, obj1)
console.log(obj2) //{ name: 'limi', age: 31, x: { y: 'z' } }

//直接操作 __proto__ 属性
let obj3 = {name:'hamey', age:30}
let obj4 = {}
obj4.__proto__ = obj3
console.log(obj4, obj4.name, obj4.age) //{} hamey 30